electrical nightmare

[new horse 44]

looking for some advice/direction, I recently bought a 1988 520H, it runs great!, but, when i bought it, none of the gauges or lights worked, I've read many, many, many of the post's in regards to wheel horse electrical issues, 520's in particular, well, today was a crappy day so I thought I'd dive into it, armed with the downloaded diagrams (from the site) and a test light, I started taking things off the tractor, removed the battery, side panel, and lower dash board to have access to whatever......... I checked for power at the backs of all the gauges and light switch and have NONE, I checked the two fuses that are along side the battery and they are both good and have power on both sides. I thought the nine pin connector was the source of my problems, after reading from others that this is a real issue, so, my plan was to get rid of it, one by one I cut and soldered/shrink tubed each wire together, while I had the battery out, i removed the bolt that grounds three different wires and cleaned each wire ring, the bolt and made sure it had a clean mounting point. I removed the ignition switch, and made sure all the terminals were clean. I was READY for some working gauges!!, but unfortunately I still have nothing, no power to any of them or the light switch. Am I missing something?? I can only find three fuses on my tractor, 2 near/along side the battery, and 1 (30amp) on the front/right corner of the engine, these all test good, with power on both sides of the fuse. Are there more fuses? I've seen pictures of a later 520 that had an actual fuse box (strip), not sure if mine is suppose to/does have one, where might it be? My tractor is MISSING both tail lights, could this be the source of my problems?? the wires are just pushed up under the seat pan. The day wasn't a total loss, I did get the oil/filter changed, hydro & filter changed and a new air filter put in, but I like it to be at 100% with all accessories working properly. Any suggestions are appreciated.

[Ed Kennell 35,769]

Your '88 520 should only have the 3 fuses that you have checked.   Do you have the demystification guide for the '88-'89 518H and 520H  pages 7-119 to 7-125 ?

The wiring diagram on page 7-120  shows two pink wires that should carry the power from the 10 amp fuse to the light switch and the gages.  So, if you have power at the fuse and none at the switch or gages, you must have a broken pink wire  terminal at the fuse block.    Check for continuity between the output side of  the fuse block to the light switch.

[new horse 44]

I will check the pink wire/10 amp fuse tomorrow. thanks for your help!

[cheesegrader 433]

Three fuses, one by the starter and two in the fuse block by the battery, is correct for that model.

I like the idea of checking for burnt pink wires leaving the 10 amp fuse.

I've had my share of that problem!

Missing tail lights should not affect power to the guages.

A bad black ground wire leaving the guages could also make that circut fail.

 

Edited May 5, 2016 by cheesegrader

[Robert of Lake Michigan 13]

You must confirm the integrity of your dash key switch.  Remove it and bench test it with a low voltage battery tester.  Look for loose crimped connectors and  check those wires with a battery light also.  12vdc is dependent on sound connections.  Separate ground wires are most reliable.  Be sure of grounding integrity.  Do not keep looking in the same place for a problem.  If you become frustrated walk away for awhile to clear your mind.

[cheesegrader 433]

Robert is right.

A bad ignition switch could also be the culprit, although you said it starts, so It wouldn't my first guess.

I have 4 520's, and I have learned the hard way to keep a few spare parts on hand.

Ignition switch about $15, voltage regulator about $20, 

relay and realy base, about 15 bucks each for sealed upgrades (Hella)

fuses, wire, fuse holders, a few bucks each.

If you are really serious, a spare carb is about $50, 

and a coil and ignition module are about $100 each.

In my (limited) experience, the most common reason for a visit from the electrical fu*k-up fairy is:

1) Burnt, shorted wires at the fuse block

2) Bad ignition switch

3) Bad relay

4) Voltage regulator

5) Burnt, shorted 9-pin connector

6) Coil

7) ignition module

 

Edited May 5, 2016 by cheesegrader

[new horse 44]

I didn't get to spend much time on it today, but I did check at the light switch (pink wire) and it is dead. after I get the lawn cut tomorrow or Saturday, there talking rain for the next few days, do, I'm planning on removing the seat pan, dash and what ever else is required to find and fix the problem. I greatly appreciate all the advice and ideas on where to look for issues. I'm going to trace the pink wire threw out the entire tractor if I have to! I need to check the accessory side of the ignition switch just to make sure the problem isn't there.

[Ed Kennell 35,769]

Yeah, if you have 12vdc at the 10 amp fuse and not at the light switch and the gages, the out lug on the fuse block has to be broken or corroded badly.

Here is the link to the wiring diagram in case you didn't find it.    Download the file, then open it and scroll down to page 7-120.

 

[new horse 44]

I would like to thank all who gave me advice on getting my 520's gauges working, I FINALLY was able to get to it yesterday (I had a heart attack three weeks ago,) as it turned out, even though, i had power at the 15 amp fuse when i tested it, test light on the top of the fuse I had nothing coming out of the fuse holder, (on the back/bottom of it) I just simply needed to clean the contacts very good, and everything came back to life!! the tach, gas gauge, hrs meter, voltmeter, and the lights now work!!! I'm sure thankful that there is a wealth of good advice in this great group.  

 

thanks guys!!!

[Ed Kennell 35,769]

   for the update on the 520.   We luv to hear we may have helped to solve a problem.   Sorry to hear you had the heart attack.  Best wishes on a complete recovery..

[AMC RULES 36,945]

 Sorry to hear, God speed on your recovery.  

[Aldon 4,826]

Good to hear both you and the horse are doing better.

[rjg854 10,737]

[953 nut 51,680]